Screw feeding device



Och 4 1932 A. L. CURRIER SCREW FEEDING DEVICE- Filed June 8.' 1928Patented Oct. 4, 1932 UNITED STATES PATENT OFFICE ARTHUR L. CURRIEB, FASHBURNHAII, MASSACHUSETTS, ASSIGNOR, BY MESNE AS- v SIGNMENTS, T0CORNELL BAG CORPORATION, A CORPORATION OF DELAWARE SCREW FEEDING DEVICEApplication led June 8, 1928. -Seria1 No. 283,785.

This invention relates to conveyors and the interior thereof a funnelshaped hopper more specifically to screw conveyors. The orcontainer,11,which is adapted to contain invention possesses manyinherent advantages 'the material to be fed into the bag. The whichrender it suitable for various uses, butl method of introducing thematerial into the 5 it is herein illustrated as applied for feedingcontainer 11, such as, for instance, that of 55 powdered, granular, orother finely divided providing predetermined charges by weight,substances. constitutes no part of the present invention,

The principal object of this invention is and it is to be understoodthat this may be to provide a conveyor which is highlypractiaccomplished in any suitable manner.

1o cal and eiicient in operation, cheaply and The amount of materialcontained in the 60 easily constructed and maintained and one hopper atany one time is also a matter which which conveys or feeds a maximumamount does not concern the present invention, this of material throughan opening of predeterhaving bearing on other conditions such as minedlimited size. i the size of the bag, etc., and is accordingly The meritsof the present invention will varied to the conditions in any particular65 appear from the following disclosure of one case. For the purpose ofillustration, it may embodiment thereof, which is given merely beconsidered that. the line 12 represents the by way of example and theutility of the inheight of the material at a period during ventionwillappear from the advantages which the device is in operation.

3 which are realized in the particular embodi- Located at the bottom ofthe container 7o ment illustrated, 1 1 is a tube 13 which projects inboth direc- The following description will be more tions beyond thecontainer 11 and extends at readily understood by referring to theacopposite Eoints through the outer can 10, as companying drawing, inwhichat 15. T e tube throughout that portionA of Figure 1 is across-sectional side elevation its length which is positioned in thecontainer 75 of a hopper, conveyor screw, and feeding 11 is providedwith an open top so as to form nozzle of a bag filling machineillustrating a semi-cylindrical trough 14. Connecting the presentinvention. the upper edges of the trough 14 and the sides Figure 2 is across-sectional view of Figure of the container 11 are shedding surfaces16 33 1, taken on the line 2-2 and looking in the which may be eitherseparatepiecesorformed 80 direction of the arrows. from the metal .outfromthe tube in the for- Figure 3 is a fragmentary, enlarged side mationof the trough. In the latter instance elevation partly in crosssectionof the conthe metal may be bent back and secured to Veyi'lg SC1` WShOWIl 111 Flgulfe 13 the sloping side walls of the container. The

5 l* igure 4 'is a fragmentary VleW 11% @FOSS Seo' outer end of the tube13 is illustrated as pro-v S5 'tion of a side elevation of a modifiedform Vined With a tapering portion 17 terminating of this HYQDOU- in anoutlet nozzle 18 of less diameter than The various novel features of theinvention the tube 13. The4 Ontiet nozzle is of usual 40 Wl appear asthe following description pro' construction and is provided with itsunder cee s.

B referring to the drawing it will be poltlon cut away .as at 19. S0-that the ma'. noted that thelinvention is illustrated as ap- ,ml lmaybedreadll-V depgslte mbo the be plied to a bag filling device of thetype in e e Ongafe upper sur ace as a wooo which the material isintroduced into a bag on@ 20 Profldod for the Purpose of osslstlflghaving n Vaive fiiiing Opening The mate in introducing the bag on to thenozzle which 5 rial isv fed through the nozzle positioned in nozzleServos to oltjhor Wholly o1' Partlauy the Hive Opening as illustratedsupport the bag while mounted thereon dur- It will be noted that theparticular device 111g the flhng Operation. The particular showncomprises a housing or can l0, which manner of supporting the bag willdepend, is of any desired shape, having mounted in however, on theotherfeatures of the filling 100 the screw 25.

core.

machine and constitutes no part of the present invention.

Surrounding the tube adjacent the tapered portion 17 is the collar 21,which may be of metal or any other suitable material which acts toreinforce the tube and to close the opening between the tube and the can10. At the opposite end of the tube 13 a bearing 22 is provided which ismounted on suitable su porting means in such manner that it serves tosupport the screw shaft 23. Inasmuch as the screw in the presentillustration is provided with no bearing at its opposite end, thebearing 22 is constructed to adequately support the screw for operation.A shoulder 24 is provided on the screw shaft, having a ybearing Contactwith the end of the bearm 22 in a manner to take the axial thrust of thescrew in operation. The screw 25 which is illustrated as an integralpart of the shaft, but which may be an independent part rigidly attachedtherewith is of a general helith cal construction, but is of particularconguration, the advantages and functions of which will be hereinaftermore fully pointed out. Located immediately above the feedin screw 25 isa second screw 26 illustrated as having a double blade terminating in ashaft mounted in a suitable bearing 28 supported in any desired mannerby the -frame of the machine. It will be noted that in the presentillustration the feeding is accomplished by a clockwise rotation fromthe screw 25, as shown in Figure 2, and in such case the upper screw 26is constructed in such manner and located in such direction that itsfeeding is in the opposite direction to that of he particular directionof rotation of the screw, of course, may be varied, provided, however,that the upper screw 6 causes a feeding of material opposite to that ofthe outward feed through the tube 1?.. Either of the shafts 23 or 27 mayconstltute a driving shaft, or each may be independently driven, but ineither case it is preferable to time their relative speeds so that thefeeding screw 25 rotates consideraby faster than the upper screw 26.

t has been found well in practice to gear the shafts 23 and 27 togetherso that the uper screw makes approximately one revo- Y ution to ninerevolutions of the lower screw.

It is further contemplated that any form of upper screw 26 beprovided-inthat the in` vention is not limited to the double blade screwillustrated, but includes any type of screw which will function toconvey the material inthe manner indicated.

By referring to Figure 3, the particular construction of the 'feedingscrew will be understood as being oner having a hollow Thecross-sectional shaft of the screw is likewise important and it will benoted that it has the outer surface30, the back surface '31, thecomparatively narrow rounded inner surface 32 and the conveying thrustsurface 33.

The modified form shown in Figure 4 is similar, in all details notshown, to the construction shown in Figure 1. The can or housing 35 isprovided with a container 36 mounted therein, having a tube 37 extendingalong its bottom projecting through the housing 35 as at 38. The tube isprovided with the shedding surfaces 39, similar to the shedding surface16 previously described. A tapering portion 40 of the tube is providedwhich terminates in the nozzle 41 having the downwardly disposed cutaway portion 42 and rounding end 43 similar in construction to thedevice shown in Figure 1. The ,collar 44 is the tapered portion 1n amanner similar to collar-21. The screw 45 in this form is provided withan extension 46 extending into the nozzle 41 for the purpose ofassisting in e conveying action. The screw portions 45 and 46 arepreferably made in the form of a single screw and their outsidedimensions are so selected that the screw properly7 fits the g tube, thetapered portion 40 and thenozzle 41, respectively.

The advantages in the present screw reside, among other things, in thecurved or angular disposition of the conveying thrust surface 33, whichhas its upper or outer edge overlapping the remaining portions of thesurface. The surface is so constructed and disposed that upon rotationthe axialthrust imparted thereby will have an inward component of forcetending to force and hold inwardly the material located between theflights of the screw. A maximum'of material can be conveyed by this formof screw'in that a relatively small portion of the convey- -ing tube 13is occupied by the screw itself,

due to the elimination of the screw shaft and `the relatively smallvolume of the screw itself. Further, due to the inward forces createdduring the feeding action, the hollow core is maintained substantiallyfilled with material being conveyed. The inner column of materiallocated within the core is carried along with the outer material inengagement with the flights in the screw, and in this manner the entirevolume of material which occupies the space both in and around the screwflights is conveyed into the feeding nozzle.

It is further found that the component forces which tend to direct thematerial inwardly of the screw act in opposition to centri fugal forcesto such an extent that it is possible to increase the feeding action byincreasing the R. P. M. of the screw considerably beyond the pointheretofore possible. With known types of screws no increased feedingaction is realized by Vincreasing the R. P. M. of the screw beyond acertain poi nt, due to the centrifugal force set up by such increase ofthe screw speed.

An additional advantage is realized in the feeding action of the presedevice in providing a screw/ of larger iameter than the outlet nozzle18. It is well known that the valve opening vof bags is limited withincertain predetermined limits to sizes which will be readily and properlyclosed by the material itself when the filled bag is removed from thenozzle of a filling machine. With this limiting feature to consider, theproblem encountered is that of introducing through an opening of aparticular size material to fill the bag in the smallest possible timeinterval. Consequently, the limitation as to speed on filling machinesheretofore has been that of the feeding screw employed for introducingmaterial through the valve opening. In the present construction it hasbeen found possible to convey material at such a. rate that the nozzle18 contains a maximum of material during the filling operation asregards fullness of the nozzle and that the rate of flow is greatly inexcess of that previously obtained. The dierence in volume of theinterior of the nozzle 18 per unit length and that of the tube 13 issubstantially equal to the volume occupied by the screw 25, so that thematerial conveyed by the screw 25 is substantially that which will'fillthenozzle 18.

In the modification shown in Figure 4 it will be obvious that the screwextension 46 will assist in conveying the material to the outlet nozzle.This form may be preferred in some instances in which, due to the natureof the material conveyed and other circumstances a better feeding actionis accomplished. I-Iere, like in the modification shown in Figure 1, itis contemplated that the relative sizes of the tube, nozzle and screwportions be so selected that the nozzle is maintained filled to maximumcapacity in operation. This may result in providing a relatively largecore for this portion of the screw so that the screw will occupy arelatively small part of the space in the nozzle. Although it is foundhighly desirable in practice to employ a construction in which a portionof the screw is larger than the nozzle for the purpose of conveying amaximum of material through an opening of limited size, it iscontemplated that many of the advantages of the present invention may berealizedby providing a screw of the construction shown in Figure 3 ofthe same size of the filling nozzle and either extending the screwbeyond the end of the container into the nozzle in a manner similar tothe device in Figure 4 or terminating the screw at the entrance to thenozzle as shown in Figure 1.

In addition to the above advantages, there is a combined operationbetween the upper screw '26 and the lower feeding screw 25. is wellknown that when material is introduced laterally iiights of a feedingscrew there is a tendency for a maximum of material to be taken from theback end of the screw. This results in some instances in the screwbeing'only partially lled. In the present devicethe upper screw 26conveys material from'the forward end of the container 11to the rearthereof in a manner to feed it into the side of the screw throughout itsentire length.' This operation combines peculiarly with the type offeeding screw illustrated to produce unexpected result-s in that theamount of material fed is greatlyl increased thereby. v It appears thatthe back feeding action of the screw 26 is more than that of a mereagitator, but is one of feeding into the screw 25 which latter screwretains substantially all of the material introduced between its flightsagainstA outward movement, such as would be caused by centrifugal forcesor other influencing factors.

Astonishing results are produced by the present mechanism and it isfound in practice that bags such as cement bags can be filled by such amachine in only a fraction of the time required by machines heretoforeknown and that excellent results are realized when the screw 25 isrotated at a speed as high as 2100 It. P. M. A machine in which thefeeding screw 25 is rotated at approximately 1900 R. P. M. and the upperscrew 26 is rotated approximately 100 R. P. M. has been found to giveadmirable results and has been employed to fill bags holdingsubstantially 100 pounds with cement in only a fraction of the timeheretofore consumed for a similar operation.

The above disclosure is given merely as one Yembodiment of the'presentinvention and' is not to be considered as limiting the invention in anyway. The scope of the invention will be determined by an understandingof the present disclosure as one embodiment thereof and will beparticularly pointedout in the appended claims.

I claim:

1. The method of discharging material which comprises introducingmaterial into a tube, exerting inward and forward pressure on thematerial adjacent the tube wall and thereby forcing forward a compactedcolumn within the tube and discharging this compacted column from theend of the tube.

2. In a device of the character described, the combination of a tubehaving a discharge opening and a conveyor screw in said tube, saidconveyor screw being constructed with a hollow core in line with saidopening and conveying surfaces disposed to exert an inward componentupon the material being conveyed, whereby to urge the material lyingadjacent the tube surfaces into the space provided by the hollow core insaid screw and to into the side between the I and having a conveyingsurface constructed to exert an inward component upon the material beingconveyed.

4. In a device of the character described, the combination of a hopperhaving a tube in side communication therewith, and an eX- tension forsaid tube of smaller diameter, constituting a filling nozzle, a spiral,hollow cored screw in the large portion of said tube adapted forrotation to feed material out through said filling nozzle, the conveyingsurface of said screw being constructed to exert an inward component onmaterial being conveyed.

5. In a device of the the combination of a hopper having a tube in sidecommunication therewith, and an extension for said tube of smallerdiameter, constituting a filling nozzle, a spiral, hollow cored screw inthe large portion of said tube adapted for rotation to feed material outthrough said filling nozzle, the capacity of said filling nozzle beingsubstantially equal to that of said tube minus the volume of said screw.

6. A filling machine comprising in combination, a hopper, a tube in sidecommunication with said hopper and a filling nozzle disposed as acontinuation of said tube, a screw having a hollow core disposed in saidtube, said filling nozzle having a diameter adapting it for insertioninto4 a bag valve opening, and said tube and screw being so proportionedas to size as to have a capacity substantially equal to the capacity ofsaid filling nozzle.

7. In a device of the character described, the combination of a hopperhaving a screw adjacent the bottom wall thereof and material shreddingsurfaces for feeding material into said screw through the side thereof,an outlet nozzle in axial communication withsaid screw, and a secondscrew disposed parallel with but above said first screw and adapted tofeed material in the opposite direction.

8. In a device of the character described,

the combination of a hopper havmg a screw adjacent the bottom wallthereof, an outlet nozzle in axial communication with said screw, and asecond screw disposed parallel with but'above said first screw andadapted to feed material in the opposite direction.

9. In a device of the character described,

character described, i

means for driving said first screw at a greater speed than said secondscrew.

10. A ban' filling .machine having in combination, a opper, a fillingnozzle, extending horizontally from said hopper, and of a size adaptingit for insertion into the valve openingof a nozzle, said screw having areduced portion to fit within said nozzle and a larger portion withinsaid hopper, the portion of said screw in said hopper having a capacitysuch as will complet-ely fill said nozzle.

11. A conveying element having a broad substantially helical face, aplow-point edge along said face, a substantially helical moldboard faceextending inwardly of said plowpoint edge, and ay cylindrical openingextending axially through said conveying element.

Signed at Fitchburg, Mass., this 4th day of June, 1928.

ARTHUR L. CURRIER.

the combination of a hopper having a screw adjacent the bottom wallthereof, an outlet nozzle in` axial communication with said screw, and asecond screw disposed parallel with but above said first screw andadapted to feed material in the opposite direction and A bag and a screwin said hopper andl

